Classifications

• • G—PHYSICS
  • G11—INFORMATION STORAGE
  • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
  • G11B5/00—Recording by magnetisation or demagnetisation of a record carrier; Reproducing by magnetic means; Record carriers therefor
  • G11B5/62—Record carriers characterised by the selection of the material
  • G11B5/64—Record carriers characterised by the selection of the material comprising only the magnetic material without bonding agent
  • G11B5/66—Record carriers characterised by the selection of the material comprising only the magnetic material without bonding agent the record carriers consisting of several layers
  • G11B5/676—Record carriers characterised by the selection of the material comprising only the magnetic material without bonding agent the record carriers consisting of several layers having magnetic layers separated by a nonmagnetic layer, e.g. antiferromagnetic layer, Cu layer or coupling layer
• • G—PHYSICS
  • G11—INFORMATION STORAGE
  • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
  • G11B5/00—Recording by magnetisation or demagnetisation of a record carrier; Reproducing by magnetic means; Record carriers therefor
  • G11B5/62—Record carriers characterised by the selection of the material
• • G—PHYSICS
  • G11—INFORMATION STORAGE
  • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
  • G11B5/00—Recording by magnetisation or demagnetisation of a record carrier; Reproducing by magnetic means; Record carriers therefor
  • G11B5/012—Recording on, or reproducing or erasing from, magnetic disks
• • G—PHYSICS
  • G11—INFORMATION STORAGE
  • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
  • G11B5/00—Recording by magnetisation or demagnetisation of a record carrier; Reproducing by magnetic means; Record carriers therefor
  • G11B5/62—Record carriers characterised by the selection of the material
  • G11B5/64—Record carriers characterised by the selection of the material comprising only the magnetic material without bonding agent
  • G11B5/65—Record carriers characterised by the selection of the material comprising only the magnetic material without bonding agent characterised by its composition
  • G11B5/656—Record carriers characterised by the selection of the material comprising only the magnetic material without bonding agent characterised by its composition containing Co
• • G—PHYSICS
  • G11—INFORMATION STORAGE
  • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
  • G11B5/00—Recording by magnetisation or demagnetisation of a record carrier; Reproducing by magnetic means; Record carriers therefor
  • G11B5/62—Record carriers characterised by the selection of the material
  • G11B5/64—Record carriers characterised by the selection of the material comprising only the magnetic material without bonding agent
  • G11B5/66—Record carriers characterised by the selection of the material comprising only the magnetic material without bonding agent the record carriers consisting of several layers
  • G11B5/672—Record carriers characterised by the selection of the material comprising only the magnetic material without bonding agent the record carriers consisting of several layers having different compositions in a plurality of magnetic layers, e.g. layer compositions having differing elemental components or differing proportions of elements
• • G—PHYSICS
  • G11—INFORMATION STORAGE
  • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
  • G11B5/00—Recording by magnetisation or demagnetisation of a record carrier; Reproducing by magnetic means; Record carriers therefor
  • G11B5/62—Record carriers characterised by the selection of the material
  • G11B5/73—Base layers, i.e. all non-magnetic layers lying under a lowermost magnetic recording layer, e.g. including any non-magnetic layer in between a first magnetic recording layer and either an underlying substrate or a soft magnetic underlayer
  • G11B5/7368—Non-polymeric layer under the lowermost magnetic recording layer
  • G11B5/7369—Two or more non-magnetic underlayers, e.g. seed layers or barrier layers
  • G11B5/737—Physical structure of underlayer, e.g. texture
• • G—PHYSICS
  • G11—INFORMATION STORAGE
  • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
  • G11B5/00—Recording by magnetisation or demagnetisation of a record carrier; Reproducing by magnetic means; Record carriers therefor
  • G11B5/62—Record carriers characterised by the selection of the material
  • G11B5/73—Base layers, i.e. all non-magnetic layers lying under a lowermost magnetic recording layer, e.g. including any non-magnetic layer in between a first magnetic recording layer and either an underlying substrate or a soft magnetic underlayer
  • G11B5/7368—Non-polymeric layer under the lowermost magnetic recording layer
  • G11B5/7379—Seed layer, e.g. at least one non-magnetic layer is specifically adapted as a seed or seeding layer
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10S428/00—Stock material or miscellaneous articles
  • Y10S428/90—Magnetic feature
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
  • Y10T428/00—Stock material or miscellaneous articles
  • Y10T428/26—Web or sheet containing structurally defined element or component, the element or component having a specified physical dimension
  • Y10T428/263—Coating layer not in excess of 5 mils thick or equivalent
  • Y10T428/264—Up to 3 mils
  • Y10T428/265—1 mil or less

Definitions

• the present invention generally relates to magnetic recording media and magnetic storage apparatuses, and more particularly to a magnetic recording medium having a seed layer and an underlayer which is made of a binary alloy, and to a magnetic storage apparatus which uses such a magnetic recording medium.
• a typical longitudinal magnetic recording medium includes a substrate, a seed layer, a Cr or Cr alloy underlayer, a Co-Cr alloy intermediate layer, a Co alloy magnetic layer where the information is written, a C overlayer, and an organic lubricant which are stacked in this order.
• Substrates that are presently used include NiP- plated Al-Mg alloy substrates and glass substrates. The glass substrate is more popular due to its resistance to shock, smoothness, hardness, light weight, and minimum flutter especially at a disk edge in the case of a magnetic disk.
• FIGS . 1 through 3 show examples of the layer structure of the conventional magnetic recording media. In FIGS. 1 through 3, those parts which are the same are designated by the same reference numerals.
• an amorphous layer 3 made of NiP on a glass substrate 1 is formed an amorphous layer 3 made of NiP.
• the NiP layer 3 is preferably oxidized.
• the second Cr underlayer 5 usually has a larger lattice parameter than the first Cr underlayer 4.
• the magnetic layer 7 has a (1120) crystallographic orientation, and may be made up of a single layer or multiple layers that are in direct contact and behave magnetically as one magnetic layer.
• An interlayer 6 made of a CoCr alloy may be disposed between the magnetic layer 7 and the Cr underlayers 4 and 5.
• elements such as Cr may be alloyed with NiP or a separate adhesive layer 2 made essentially of Cr may be employed.
• a protective layer 8 made of C, and an organic lubricant layer 9 are deposited for use with a magnetic transducer such as a spin- valve head.
• the structure is similar to that of FIG. 1.
• the magnetic layer 7 is replaced by a plurality of layers 7-a and 7-b that are antiferromagnetically coupled through a spacer layer 10 made of Ru , so as to form a so-called synthetic ferrimagnetic medium (SFM) .
• the first layer 7-a functions as a stabilizing layer
• the second layer 7-b functions as a main recording layer.
• a third example shown in FIG. 3 utilizes a refractory metal seed layer 3-a made of Ta-M, where M is either nitrogen or oxygen.
• a Ta-M seed layer 3-a either by reactive sputtering with Ar + N 2 or Ar + 0 2 gas on which an underlayer 4 is deposited.
• the crystallographic orientation of (002) is mentioned in a United States Patent No .5 , 685 , 958 , but the composition of the underlayer is limited to Cr or Cr alloy, and no mention is made of underlayers made of materials such as B2 structured materials, for example.
• the magnetic layer 7 is formed on the interlayer 6 or the underlayer 5 with a (1120) preferred orientation as in the first example described above.
• the microstructure of the magnetic layer which includes grain size, grain size distribution, preferred orientation and Cr segregation strongly affect recording characteristics of the magnetic recording medium.
• the microstructure of the magnetic layer is usually controlled by the use of one or more seed layers and one or more underlayers .
• NiP is used as the seed layer on a suitable substrates made of glass or aluminum.
• Various seed layer materials such as CoCrZr, NiAl and RuAl may be used to obtain in-plane magnetization required for the longitudinal recording.
• the AlRu seed layer has become more popular due ⁇ to its influence on the strong texture growth of the subsequent underlayers and magnetic recording layers. Also the AlRu seed layer was found to reduce grain sizes of the subsequent underlayers and the magnetic layers .
• AlRu is a B2 structured material in composition ranges of 50% Ru and 50 % Al . Though B2 structured AlRu is useful, it is increasingly demanding to search for other composition ranges of AlRu.
• One way to approach the problem is to sputter deposit from two different targets respectively purely made of Al and Ru in the same chamber, that is, to employ a multicathode system. By varying the power ratios between the two targets, it is easy to study large composition ranges which are otherwise quite expensive using various single alloy targets made of AlRu alloys.
• Such a multicathode system offers new ways to search for composition ranges which give the B2 structure of AlRu.
• AlRu 50 when used as a single alloy target, it is very easy to form, under normal sputtering parameters, a (001) texture on top of which grows Cr(002) and Co alloy magnetic layer with (1120) texture.
• films are deposited with Al and Ru using the multicathode system, practically it is very difficult to form a good (002) in-plane texture of AlRu 50 .
• Another and more specific object of the present invention is to provide a magnetic recording medium comprising a substrate; a magnetic recording layer made of a Co alloy or a CoCr alloy; a seed layer disposed between the substrate and the magnetic recording layer; and an underlayer made of a binary alloy material having a B2 structure and disposed between the seed layer and the magnetic recording layer, where the seed layer is made of a material comprising essentially of one of elements forming the binary alloy material of the underlayer.
• the magnetic recording medium of the present invention it is possible to reduce grain sizes of the underlayer and the magnetic recording layer, and promote desired orientation of the magnetic recording layer. As a result, it is possible to realize a magnetic recording medium having an improved performance.
• Still another object of the present invention is to provide a magnetic storage apparatus comprising at least one magnetic recording medium comprising a substrate, a magnetic recording layer made of a Co alloy or a CoCr alloy, a seed layer disposed between the substrate and the magnetic recording layer, and an underlayer made of a binary alloy material having a B2 structure and disposed between the seed layer and the magnetic recording layer, the seed layer being made of a material comprising essentially of one of elements forming the binary alloy material of the underlayer; and a head which writes information on and/or reproduces information from the magnetic recording medium.
• the magnetic storage apparatus of the present invention it is possible to realize a magnetic storage apparatus having an improved performance, because of the reduced grain sizes of the underlayer and the magnetic recording layer and the promoted desired orientation of the magnetic recording layer of the magnetic recording medium.
• FIG. 1 is a cross sectional view showing a part of a first example of a conventional magnetic recording medium
• FIG. 2 is a cross sectional view showing a part of a second example of the conventional magnetic recording medium
• FIG. 3 is a cross sectional view showing a part of a third example of the conventional magnetic recording medium
• FIG. 4 is a cross sectional view showing an important part of a first embodiment of a magnetic recording medium according to the present invention
• FIG. 5 is a cross sectional view showing an important part of a second embodiment of the magnetic recording medium according to the present invention
• FIG. 6 is a cross sectional view showing an important part of a third embodiment of the magnetic recording medium according to the present invention.
• FIG. 7 is a diagram showing XRD spectrums of AlRu samples co-sputtered from Al and Ru targets for different AlRu thicknesses
• FIG. 8 is a diagram showing XRD spectrums of AlRu samples co-sputtered from Al and Ru targets for different substrate temperatures ;
• FIG. 9 is a diagram showing XRD spectrums of AlRu samples co-sputtered from Al and Ru targets for different sputtering Ar pressures
• FIG. 10 is a diagram showing an XRD spectrum of AlRu samples co-sputtered from Al and Ru targets by applying a substrate bias of -150V;
• FIG. 11 is a diagram showing a perpendicular Kerr loop obtained for a AlRu/CrMo/CoCrPtB structure
• FIG. 12 is a diagram showing a schematic representation of a substrate biasing effect and AlRu initial film growth
• FIG. 13 is a diagram for explaining the substrate biasing effect and the AlRu initial film growth
• FIG. 14 is a diagram showing a (001) texture of AlRu, where only one type of element is present in the same plane;
• FIG. 15 is a diagram showing XRD spectrums of Glass/Al/AlRu/CrMo/CoCrPtB/ structures, where a predominant (001) texture of AlRu exists;
• FIG. 16 is a diagram showing XRD spectrums of Glass/Ru/AlRu/CrMo/CoCrPtB/ structures, where AlRu has a predominant (001) texture;
• FIG. 17 is a diagram showing perpendicular coercivity values of Al (or Ru) /AlRu/CrMo/CoCrPtB/ structures ;
• FIG. 18 is a cross sectional view showing an important part of this embodiment of the magnetic storage apparatus.
• FIG. 19 is a plan view showing the important part of the embodiment of the magnetic storage apparatus .
• FIG. 4 is a cross sectional view showing an important part of a first embodiment of a magnetic recording medium according to the present invention.
• a seed layer 13 and an underlayer 14 made of an intermetallic binary alloy are deposited on a glass or Al substrate 11 .
• the seed layer 13 is made essentially of one of the elements of binary alloy underlayer 14.
• the seed layer 13 may be reactively sputtered with N 2 or 0 2 partial pressures, for example.
• a magnetic layer 17 made of a Co alloy or a CoCr alloy.
• the magnetic layer 17 has a (1120) crystallographic orientation, and may be made up of a single layer or multiple layers that are in direct contact and behave magnetically as one magnetic layer.
• a protective layer 18 made of C, and an organic lubricant layer 19 are deposited for use with a magnetic transducer such as a spin-valve head.
• the glass or Al substrate 11 may be mechanically textured.
• the underlayer 14 is made of a binary alloy such as AlRu, preferably B2 structured.
• the binary alloy used promote lattice matching and crystallographic orientation of subsequent layers .
• RuAl , CoTi or the like are useful for obtaining a good lattice matching with the (002) growth of Cr and subsequent (1120) texture of magnetic layers.
• the underlayer may be made of B2 structured materials such as RuAl, NiAl , CoAl , FeAl , FeTi, CoHf, CoZr, NiTi, CuBe, CuZn, AlMn, AlRe, AgMg, MnRh , IrAl and OsAl which have approximately 40% to 60% composition ranges of one of the elements.
• the underlayer material forming B2 structure may be deposited by sputtering from two separate metal targets or from separate metal targets whose compositions are predominantly formed from one type of material of the binary alloy.
• the underlayer 14 is deposited to a thickness of approximately 5 nm to 60 nm, for example.
• the seed layer 13 which functions as a buffer layer, is deposited prior to the underlayer 14, and is made of one of the elements which makes the binary alloy forming the underlayer 14.
• an Al or Ru seed layer 13 is used for an AlRu underlayer
• a Fe or Ti seed layer 13 is used for a FeTi underlayer 14.
• the seed layer 13 may essentially be made of a metal nitride or oxide of one of the elements which makes the binary alloy forming the underlayer 14.
• an Al-N or Al-0 seed layer 13 may be used for an AlRu underlayer 14, and a Ti-0 or Ti-N seed layer 13 may be used for a FeTi underlayer 14.
• the metal nitride or oxide seed layer 13 promotes an excellent crystallographic orientation for the underlayer 14 and provides excellent (002) growth for Cr based subsequent layers and very good (1120) texture for the magnetic layer 17.
• the seed layer 13 is deposited to a thickness of approximately 0.5 nm to 50 nm, for example. Desirably, a total thickness of the seed layer 13 and the underlayer 14 is approximately 30 nm to 60 nm. This desired range of the total thickness can be deposited in just two chambers and reduces the drop in glass substrate temperature during deposition of subsequent layers.
• the seed layer 13 may be processed under a suitable temperature range of approximately 100 °C to 230°C with a pressure of approximately 5 mTorr to 50 mTorr with or without the substrate bias .
• the substrate bias may be applied to a metallic substrate made of a material such as Al , however, a pre-seed layer made of a material such as Cr is desired for biasing when using a glass substrate.
• the protective layer 18 is made of C having a thickness of approximately 1 nm to 5 nm, for example.
• the organic lubricant layer 19 has a thickness of approximately 1 nm to 3 nm.
• the C protective layer 18 may be deposited by CVD is hard, and protects the magnetic recording medium not only from atmospheric degradation but also from physical contacts with the head.
• the lubricant layer 19 reduces stiction between the head and the magnetic recording medium.
• FIG. 5 is a cross sectional view showing an important part of a second embodiment of the magnetic recording medium according to the present invention.
• those parts which are the same as those corresponding parts in FIG. 4 are designated by the same reference numerals, and a description thereof will be omitted.
• FIG. 6 is a cross sectional view showing an important part of a third embodiment of the magnetic recording medium according to the present invention.
• those parts which are the same as those corresponding parts in FIG. 4 are designated by the same reference numerals, and a description thereof will be omitted.
• a lattice matching layer 15 may be disposed between the magnetic layer structure (17-a, 17-b) and the underlayer 14 for lattice matching with the magnetic layer structure (17-a, 17-b) and prevention of diffusion from the underlayer 14 into the magnetic layer structure (17-a, 17-b) .
• An hep interlayer 16 may be inserted between the magnetic layer structure (17-a, 17-b) and the underlayer 14.
• the hep interlayer 16 also serves as a buffer between the bcc underlayer 14 and the hep magnetic layer structure (17-a, 17-b) .
• the lattice matching layer 15 may be made of Cr-M layer and deposited to a thickness of approximately 1 nm to 10 nm, where M is a material selected from a group consisting of Mo, Ti, V, and W with an atomic proportion greater than or equal to 10%.
• the lattice matching layer 14 may be made essentially of Ru having a thickness of approximately 1 nm to 3 nm. However, since the lattice parameters of the Ru lattice matching layer 15 are larger than those of the Co alloy or CoCr alloy used for the magnetic layers 17-a and 17-b, the Ru lattice matching layer 15 cannot be too thick,
• the hep interlayer 16 is made of a slightly magnetic or nonmagnetic hep structured CoCr alloy which is deposited to a thickness of approximately 1 nm to 5 nm.
• the hep structured CoCr alloy includes CoCrPtB, CoCrPt, CoCrTa, CoCrPtTa, CoCrPtTaB and the like.
• the in-plane orientation of the magnetic layer structure is improved as the interlayer 16 functions to gradually match the lattice parameters, and the full magnetization of the magnetic layer structure is obtained, that is, the so-called "dead layer” is minimized. Moreover, the formation of smaller grains at the interface of the magnetic layer structure is also minimized.
• the SFM has an improved thermal stability but require excellent in-plane orientation which is provided by the above described combination of the seed layer 13 and the underlayer 14.
• the embodiments described above provide a scheme for making a (001) texture from a B2 structured alloy or a binary alloy.
• the first deposited seed layer 13 on the substrate 11 needs to be made of one of elements forming binary alloy of the underlayer 14. This fact is made use to define a very thin and preferably a monolayer metal ' film as the seed layer 13.
• the deposition condition for the underlayer material such as AlRu is crucial for developing the desired texture, especially when deposited using the multicathode system where pure metallic targets are co-sputtered with different power ratios to obtain the desired texture.
• Most important deposition conditions which describe the proper texture are substrate temperature, thicknesses of films, sputtering pressure and substrate bias. A description will now be given of the AlRu growth properties for different deposition (sputtering) conditions.
• FIGS . 7 through 9 show XRD spectrums of AlRu/CrMo/CoCrPtB structures deposited at different sputtering conditions for the AlRu underlayer 14.
• Each AlRu/CrMo/CoCrPtB structure is made up of the AlRu underlayer 14, the CrMo lattice matching layer 15, and the CoCrPtB interlayer 16.
• the AlRu underlayer 14 is formed by co-sputtering from two different pure metal targets of Al and Ru .
• An Al 50 Ru 50 composition can be easily obtained by changing the power ratios applied between the two targets .
• the ordinate indicates the intensity in arbitrary units (A.U.)
• the abscissa indicates 2 ⁇ (degrees) .
• FIG. 7 is a diagram showing XRD spectrums of AlRu samples co-sputtered from Al and Ru targets for different AlRu thicknesses.
• FIG, 7 shows the XRD spectrum of the AlRu samples with different AlRu layer thicknesses ranging from 3 nm to 100 nm.
• Curves 101, 102 and 103 respectively correspond to AlRu layer thicknesses of 3 nm, 20nm and 100 nm.
• a prominent peak appears near 2e of approximately 43°. This peak corresponds to AlRu (110) which is not a desired texture for the subsequent Cr and magnetic recording layer 17.
• the texture which is of interest is the AlRu (002) which has the XRD peak around 2e of approximately 30° which will give
• FIG. 8 is a diagram showing XRD spectrums of AlRu samples co-sputtered from Al and Ru targets for different substrate temperatures.
• FIG. 8 shows the effect of the substrate temperature on the growth of AlRu layer.
• Curves 201, 202, 203 and 204 respectively correspond to substrate temperatures of 230°C, 200°C, 150°C and 0°C.
• Ar pressure used for the sputtering was kept at 5 mTorr and the AlRu layer thickness was kept constant at 20 nm.
• the substrate temperature was changed from 0°C to 230°C. It is clear from the FIG. 8 again that AlRu (110) texture is dominant and AlR (002) texture is clearly absent.
• FIG. 9 is a diagram showing XRD spectrums of AlRu samples co-sputtered from Al and Ru targets for different sputtering Ar pressures. Curves 301, 302 and 303 respectively correspond to Ar pressures of 5 mTorr, 20 mTorr and 50 mTorr. In this case also, the required AlRu (002) texture is clearly absent.
• FIG. 10 is a diagram showing an XRD spectrum of AlRu samples co-sputtered from Al and Ru targets by applying a substrate bias of -150V.
• the ordinate indicates the intensity in arbitrary units (A.U.)
• the abscissa indicates 2 ⁇ (degrees) .
• FIG. 11 is a diagram showing a perpendicular Kerr loop obtained for a AlRu/CrMo/CoCrPtB structure, where the AlRu under layer 14 is 100 nm, the CrMo lattice matching layer 15 is 5 nm and the CoCrPtB interlayer 16 is 18 nm.
• the ordinate indicates the Kerr rotation (degrees)
• the abscissa indicates the applied field (kOe) .
• the substrate biasing it is necessary to deposit a thin layer of Cr/NiP before an AlRu layer.
• the growth properties are slightly different for the two layers, but it gives the clue as to what causes the absence of growth of AlRu (002) .
• the substrate temperature was 150°C and a substrate bias of -150 V was applied. In this case, a predominant AlRu (001) growth was observed, along with a relatively much lower AlRu (110) texture.
• FIG. 12 is a diagram showing a schematic representation of a substrate biasing effect and AlRu initial film growth.
• reference numerals 501 and 502 respectively denote an Ru target and an Al target.
• FIG. 13 is a diagram for explaining the substrate biasing effect and the AlRu initial film growth.
• the left part indicates the (001) and (110) growths on the substrate 11, and the right part indicates the Al and Ru sputtered on the substrate 11 with substrate biasing. It may be understood from the description given heretofore that it is important to add a thin layer of metal (seed layer 13) prior to depositing a layer of the binary alloy (underlayer 14) . This enables the growth of (001) texture whose surface- is made predominantly of one type of elements as is clear from FIG. 14.
• FIG. 14 is a diagram showing a (001) texture of AlRu, where only one type of element is present in the same plane.
• FIG. 14 shows the texture of AlRu cell structure.
• one surface contains always the same element, namely, Ru or Al .
• Such growth can be imparted by pre- depositing a pure Al or Ru seed layer 13 prior to the AlRu underlayer 14. This could be applicable to any binary alloy preferably B2 structured ones where the seed layer consists of a thin predominantly containing one of the pure element, prior to the deposition of the binary alloy. This method is tried as an example in the formation of AlRu layer.
• FIG. 15 is a diagram showing XRD spectrums of Glass/Al/AlRu/CrMo/CoCrPtB structures, where a predominant (001) texture of AlRu exists.
• FIG. 15 shows the XRD pattern taken from Glass/Al/AlRu/CrMo/CoCrPtB structures for various thicknesses of Al .
• Each Glass/Al/AlRu/CrMo/CoCrPtB structure is made up of the glass substrate 11, the Al seed layer 13, the AlRu underlayer 14, the CrMo lattice matching layer 15, and the CoCrPtB interlayer 16.
• Curves 401, 402 and 403 respectively correspond to a case where the Al seed layer 13 is 3 nm and the AlRu underlayer 14 is 30 nm, a case where the Al seed layer 13 is 1 nm and the AlRu underlayer 14 is 30 nm, and a case where the Al seed layer 13 is 3 nm and the AlRu underlayer 14 is 100 nm. It 'is clear that by introducing a very thin Al seed layer 13, the AlRu (001) texture is easily formed.
• FIG. 16 is a diagram showing XRD spectrums of Glass/Ru/AlRu/CrMo/CoCrPtB/ structures, where AlRu has a predominant (001) texture.
• FIG. 16 shows the XRD pattern taken from Glass/Ru/AlRu/CrMo/CoCrPtB structures for various thicknesses of Ru .
• Each Glass/Ru/AlRu/CrMo/CoCrPtB structure is made up of the glass substrate 11, the Ru seed layer 13, the AlRu underlayer 14, the CrMo lattice matching layer 15, and the CoCrPtB interlayer 16.
• Curves 601, 602 and 603 respectively correspond to a case where the Ru seed layer 13 is 1 nm and the AlRu underlayer 14 is 30 nm, a case where the Ru seed layer 13 is 3 nm and the AlRu underlayer 14 is 30 nm, and a case where the Ru seed layer 13 is 3 nm and the AlRu underlayer 14 is 100 nm.
• FIG. 17 is a diagram showing perpendicular coercivity values of Al (or Ru) /AlRu/CrMo/CoCrPtB structures.
• FIG. 17 shows the perpendicular coercivity values of Al (or Ru) /AlRu/CrMo/CoCrPtB structure measured using Kerr measurements.
• the ordinate indicates the perpendicular coercivity (Oe)
• the abscissa indicates the thickness (nm) of the Al (or Ru) seed layer 13.
• a symbol O indicates the coercivity for the Al/AlRu seed layer and underlayer combination
• a symbol # indicates the coercivity for the Ru/RuAl seed layer and underlayer combination.
• a suitable substrate temperature range of approximately 100°C to 230°C gives good crystallographic texture and good adhesion of the layers. However, for different binary alloy systems and for different texture requirements , the substrate temperature may be appropriately adjusted to obtain the same effects.
• a wide sputtering gas pressure range of 5 mTorr to 50 mTorr may be used with or without the substrate bias . These are the usual sputtering conditions employed to produce the magnetic recording medium.
• Substrate bias can be applied to a metallic substrate made of Al or the like, however, a metallic pre-seed layer made of a material such as Cr is essential for biasing if using the glass substrate .
• GaAs(lOO) texture is very much used in the present day material for obtaining particular orientation (or texture) in semiconductor devices. Normally, a single crystal substrate is preferred in such cases. However, with sputtering, such a texture can be easily grown by depositing Ga first and then depositing the GaAs together to make the (001) texture.
• texture which can be imparted using the present invention, that is, to employ a predominantly single atomic species prior to depositing a binary alloy or a tertiary alloy comprising predominantly two species.
• Some of the textures which can be imparted may be a (112) texture of NiAl or FeAl or similar materials.
• a perpendicular anisotropy can also be imparted for a Co alloy magnetic layer for application to a perpendicular magnetic recording.
• a Co (0002) texture of the magnetic layer is imparted from the combination of a thin single atomic species layer and a binary (or tertiary) alloy layer.
• the present invention may similarly be applied to other kinds of substrates, such as metal, polymer, plastic and ceramic substrates which may be flexible or rigid, and still not depart from the spirit of the present invention.
• substrates such as metal, polymer, plastic and ceramic substrates which may be flexible or rigid, and still not depart from the spirit of the present invention.
• mechanical circumferential texturing texturing parallel to tracks
• NiP coated substrates are found to have much superior performance than that without such texturing, in terms of the signal-to- noise (S/N) ratio and in terms of thermal decay.
• S/N signal-to- noise
• (1120) texture are oriented mostly along the circumferential direction in the case of the magnetic disk, this texturing is added advantage for the magnetic recording, because the head field is also applied along the circumferential direction during operation.
• mechanical texturing applied on the NiP coated substrates imparts crystallographically alignment not only the magnetic layer, but also on the Cr alloy underlayers. Underlayers are grown with (002) texture both with and ' without mechanical texturing.
• the Cr ⁇ 110> direction is also preferably aligned towards the circumferential direction in the case of the magnetic disk. Therefore, the magnetic recording medium of the present invention would also show preferable underlayer and magnetic layer orientation due to either the mechanical texturing of the substrate or due to the mechanical circumferential texturing of the seed layer such as NiP or the seed layer according to the present invention.
• FIG. 18 is a cross sectional view showing an important part of this embodiment of the magnetic storage apparatus
• FIG. 19 is a plan view showing the important part of this embodiment of the magnetic storage apparatus.
• the magnetic storage apparatus generally includes a motor 114, a hub 116, a plurality of magnetic recording media 116, a plurality of recording and reproducing heads 117, a plurality of suspensions 118, a plurality of arms 119, and an actuator unit 120 which are provided within a housing 113.
• the magnetic recording media 116 are mounted on the hub 115 which is rotated by the motor 114.
• the recording and reproducing head 117 is made up of a reproducing head such as a MR or GMR head, and a recording head such as an inductive head.
• Each recording and reproducing head 117 is mounted on the tip end of a corresponding arm 119 via the suspension 118.
• the arms 119 are moved by the actuator unit 120.
• This embodiment of the magnetic storage apparatus is characterized by the magnetic recording media 116.
• Each magnetic recording medium 116 has the structure of any of the embodiments described above described in conjunction with FIGS. 4 through 17.
• the number of magnetic recording media 116 is not limited to three and only two or four or more magnetic recording media 116 may be provided.
• the basic construction of the magnetic storage apparatus is not limited to that shown in FIGS. 18 and 19.
• the magnetic recording medium used in the present invention is not limited to a magnetic disk, and the magnetic recording medium may take the form of a magnetic tape, a magnetic card or the like. Therefore, according to the present invention, it is possible to reduce grain sizes of the underlayer and the magnetic recording layer, and promote desired orientation of the magnetic recording layer, by the provision of the seed layer. As a result, it is possible to realize a magnetic recording medium having an improved performance, even when the underlayer is formed using the multicathode system. Of course, when the single-cathode system is used to form the underlayer, the grain sizes of the underlayer and the magnetic recording layer can similarly be reduced to promote the desired orientation of the magnetic recording layer by the provision of the seed layer.

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• 2002
  • 2002-09-06 WO PCT/JP2002/009128 patent/WO2004027762A1/en active IP Right Grant
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